Analysis of the intestinal immune response to Giardia species in cattle and mice

The protozoan parasite Giardia duodenalis is a highly present pathogen around the globe in a vast array of hosts. Once ingested, Giardia can induce intestinal symptoms and could cause significant production losses in animals such as cattle. Although infections can pass by unnoticed and rapidly, a number of patients experience giardiosis as a persistent and chronic disease. Although we have already some knowledge on the immune response in natural hosts, the reason behind the observed chronicity is still unclear and Giardia induced host-pathogen interactions remain incompletely defined. The first step in the research presented in this thesis was to investigate the intestinal response in calves following a G. duodenalis infection using a bovine high-density oligo microarray to analyze global gene expression in the small intestine. The resulting data suggested a decrease in inflammation, immune response, and immune cell migration in infected animals. Quantitative real-time PCR revealed that he transcription levels of IL-6, IL-8, IL-13, IL-17, and IFN-γ showed a trend of being downregulated in the jejunum of infected animals compared to the negative controls. No immune cell recruitment could be seen after infection using histological stainings, and no intestinal pathologies, such as villus shortening or increased levels of apoptosis. Possible regulators of this intestinal response were the nuclear peroxisome proliferator-activated receptors alpha (PPARα), and gamma (PPARγ), all for which an upregulated expression was found in the microarray and qRT-PCR analyses. To gather further insights in the intestinal host response a murine giardiosis model was used where BALB/c and C57Bl/6 mice are infected with their natural parasite Giardia muris. In all mice, a strong up-regulation of Il17a could be observed starting around 1 week post infection. The significance of IL-17A in orchestrating a protective immune response was unequivocally demonstrated in an infection trial using IL-17 receptor A C57Bl/6 KO mice: whereas in wild type mice cyst excretion dropped significantly after 3 weeks of infection, the KO mice were unable to clear infection. No up-regulation could be seen for PPARγ in both mice strains, and in addition, no up-regulated expression was seen for PPARα in BALB/c animals. Analysis of the intestinal response in C57Bl/6 mice however revealed a PPARα induction soon after the initial contact with the parasite, as characterized by the transcriptional up-regulation of Ppara itself and several downstream target genes such as Pltp and Cpt1. This induction of PPARα did not seem to influence the immune response against G. muris since BALB/c mice administrated with a PPARα agonist and PPARα KO C7Bl/6 animals expressed Il17a and could clear the infection similar to WT controls. Overall, we concluded that IL-17A is likely to be a crucial cytokine in the response to Giardia infection and the elimination of the parasite. In cattle it seemed that the PPARs were responsible for the lack of immune response because of their anti-inflammatory and immune suppressing characteristics, but this could not be clarified in G. muris infected mice when looking at PPARα. This nuclear receptor showed an up-regulation early on in infection but did not seem to influence infection duration

Giardia muris infection in mice is associated with the intestinal activation of the Peroxisome Proliferator-Activated Receptor Alpha followed by a protective IL-17A response

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Unraveling the role of IL-17A in the intestinal immune response against the protozoan parasite Giardia muris by an RNA sequencing approach

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Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum

The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells

Prediction of functional outcome after acute ischemic stroke : comparison of the CT-DRAGON score and a reduced features set

Background and Purpose:The CT-DRAGON score was developed to predict long-term functional outcome after acute stroke in the anterior circulation treated by thrombolysis. Its implementation in clinical practice may be hampered by its plethora of variables. The current study was designed to develop and evaluate an alternative score, as a reduced set of features, derived from the original CT-DRAGON score. Methods:This single-center retrospective study included 564 patients treated for stroke, in the anterior and the posterior circulation. At 90 days, favorable [modified Rankin Scale score (mRS) of 0-2] and miserable outcome (mRS of 5-6) were predicted by the CT-DRAGON in 427 patients. Bootstrap forests selected the most relevant parameters of the CT-DRAGON, in order to develop a reduced set of features. Discrimination, calibration and misclassification of both models were tested. Results:The area under the receiver operating characteristic curve (AUROC) for the CT-DRAGON was 0.78 (95% CI 0.74-0.81) for favorable and 0.78 (95% CI 0.72-0.83) for miserable outcome. Misclassification was 29% for favorable and 13.5% for miserable outcome, with a 100% specificity for the latter. National Institutes of Health Stroke Scale (NIHSS), pre-stroke mRS and age were identified as the strongest contributors to favorable and miserable outcome and named the reduced features set. While CT-DRAGON was only available in 323 patients (57%), the reduced features set could be calculated in 515 patients (91%) (p < 0.001). Misclassification was 25.8% for favorable and 14.4% for miserable outcome, with a 97% specificity for miserable outcome. The reduced features set had better discriminative power than CT-DRAGON for both outcomes (both p < 0.005), with an AUROC of 0.82 (95% CI 0.79-0.86) and 0.83 (95% CI 0.77-0.87) for favorable and miserable outcome, respectively. Conclusions:The CT-DRAGON score revealed acceptable discrimination in our cohort of both anterior and posterior circulation strokes, receiving all treatment modalities. The reduced features set could be measured in a larger cohort and with better discrimination. However, the reduced features set needs further validation in a prospective, multicentre study

Migratory CD103+ dendritic cells suppress helminth-driven type 2 immunity through constitutive expression of IL-12

CD8alpha(+) and CD103(+) dendritic cells (DCs) play a central role in the development of type 1 immune responses. However, their role in type 2 immunity remains unclear. We examined this issue using Batf3(-/-) mice, in which both of these DC subsets are missing. We found that Th2 cell responses, and related events such as eosinophilia, alternative macrophage activation, and immunoglobulin class switching to IgG1, were enhanced in Batf3(-/-) mice responding to helminth parasites. This had beneficial or detrimental consequences depending on the context. For example, Batf3 deficiency converted a normally chronic intestinal infection with Heligmosomoides polygyrus into an infection that was rapidly controlled. However, liver fibrosis, an IL-13-mediated pathological consequence of wound healing in chronic schistosomiasis, was exacerbated in Batf3(-/-) mice infected with Schistosoma mansoni. Mechanistically, steady-state production of IL-12 by migratory CD103(+) DCs, independent of signals from commensals or TLR-initiated events, was necessary and sufficient to exert the suppressive effects on Th2 response development. These findings identify a previously unrecognized role for migratory CD103(+) DCs in antagonizing type 2 immune responses

The efficacy of a treatment with fenbendazole against an experimental Giardia duodenalis infection in lambs

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